645640610 has 16 divisors (see below), whose sum is σ = 1164123576. Its totient is φ = 257818368.

The previous prime is 645640607. The next prime is 645640643. The reversal of 645640610 is 16046546.

It can be written as a sum of positive squares in 4 ways, for example, as 627552601 + 18088009 = 25051^2 + 4253^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48509 + ... + 60368.

Almost surely, 2^645640610 is an apocalyptic number.

645640610 is a deficient number, since it is larger than the sum of its proper divisors (518482966).

645640610 is a wasteful number, since it uses less digits than its factorization.

645640610 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109477.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 645640610 is about 25409.4590654740. The cubic root of 645640610 is about 864.2982089971.

The spelling of 645640610 in words is "six hundred forty-five million, six hundred forty thousand, six hundred ten".